Elastin obtained from the lungs of cockerels, rats, and other species will be compared after isolation and characterization. The major emphasis will be placed on elucidating the nature and forms of precursors to fibrous elastin. These forms of elastin will be obtained by first retarding intra- and intermolecular crosslinking either by nutritional copper-deficiency or administering lathyritic agents. The tests for the degree of homology between various elastins will be based on amino acid composition, electrophoretic mobility, chromatographic behavior, peptide mapping, immunochemical properties, and when possible N-terminal amino acid sequence data. The primary purpose of this part of the investigation will be to provide basic information on the properties of lung elastin so that studies on lung elastin metabolism will be made more feasible. Elastin metabolism and turnover in response to lung injury will also be investigated. The effects of bleomycin, paraquot, and metals, such as Cd, Zn, or Cu will be subject of these investigations, since each agent has been shown in some way to influence the overall metabolism of elastin. With respect to bleomycin and paraquot, experiments will be performed to determine if elastin synthesis is increased. High dietary Zn, exposure to cadmium and copper-deficiency appear to effect the net destruction of elastic fibers. The mechanism of action of these agents will be explored as a means of better understanding elastin metabolism in general.